Hydrophilic treatment coating composition and hydrophilizing treatment method

1. A hydrophilic treatment method, comprising:

treating a surface layer that contains an inorganic compound with a silane coupling agent that contains a radical reactive functional group;

applying a hydrophilic treatment coating composition to the surface layer that is coupled with the silane coupling agent, the hydrophilic treatment coating composition containing a hydrophilic compound that contains a radical reactive functional group and an alkali metal salt of a sulfonic acid group, does not contain a hydrophilic portion at a site other than an end of a molecular chain, and does not contain a branched chain, a radical polymerization initiator, and a polar compatibilizer; and

allowing the radical reactive functional group of the silane coupling agent and the radical reactive functional group of the hydrophilic compound to react with each other with a radical that occurs from the radical polymerization initiator due to light or heat, wherein

the polar compatibilizer is at least one member selected from the group consisting of urea, melamine, acryloyl morpholine, dimethyl acrylamide, dimethylaminopropyl acrylamide, isopropyl acrylamide, diethyl acrylamide, hydroxyethyl acrylamide, dimethyl sulfoxide, acetonitrile, N,N-dimethylformamide, ethylene glycol, glycerin, trimethylolpropane, ditrimethylolpropane, erythritol, dipentaerythritol, triose, tetrose, pentose, hexose, sedoheptulose, glucose, maltose, sucrose, lactose, cellobiose, raffinose, acarbose, oligosaccharides, cyclodextrin, dextrin, starch, sodium carboxymethyl cellulose, polyvinyl pyrrolidone, sodium polyacrylate, sodium hydrogen carbonate, sodium carbonate, sodium hydrogen sulfate, and sodium sulfate.

2. A hydrophilic treatment method, comprising:

treating a surface layer that contains an inorganic compound with a silane coupling agent that contains a radical reactive functional group;

applying a hydrophilic treatment coating composition to the surface layer that is coupled with the silane coupling agent, the hydrophilic treatment coating composition containing a compound that contains a radical reactive functional group and a sulfonic acid group, does not contain a hydrophilic portion at a site other than an end of a molecular chain, and does not contain a branched chain, a radical polymerization initiator, and a polar compatibilizer;

allowing the radical reactive functional group of the silane coupling agent and the radical reactive functional group of the compound to react with each other with a radical that occurs from the radical polymerization initiator due to light or heat; and

allowing the sulfonic acid group of the compound to react with a hydroxide of an alkali metal to form sulphonate.

3. A hydrophilic treatment method, comprising:

treating a surface layer that contains an inorganic compound with a silane coupling agent that contains at least one reactive functional group selected from an isocyanate group, an epoxy group, an amino group, and a mercapto group;

applying a hydrophilic treatment coating composition to a surface layer that is coupled with the silane coupling agent, the hydrophilic treatment coating composition containing a hydrophilic compound that contains a functional group that is at least one selected from an amino group, a hydroxyl group, and a mercapto group, and reacts with the reactive functional group of the silane coupling agent, and sulfonic acid or an alkali metal salt of the sulfonic acid group, and which does not contain a hydrophilic portion at a site other than an end of a molecular chain, and a polar compatibilizer; and

allowing the reactive functional group of the silane coupling agent and the functional group of the hydrophilic compound to react with each other by heat, wherein

the polar compatibilizer is at least one member selected from the group consisting of urea, melamine, acryloyl morpholine, dimethyl acrylamide, dimethylaminopropyl acrylamide, isopropyl acrylamide, diethyl acrylamide, hydroxyethyl acrylamide, dimethyl sulfoxide, acetonitrile, N,N-dimethylformamide, ethylene glycol, glycerin, trimethylolpropane, ditrimethylolpropane, erythritol, dipentaerythritol, triose, tetrose, pentose, hexose, sedoheptulose, glucose, maltose, sucrose, lactose, cellobiose, raffinose, acarbose, oligosaccharides, cyclodextrin, dextrin, starch, sodium carboxymethyl cellulose, polyvinyl pyrrolidone, sodium polyacrylate, sodium hydrogen carbonate, sodium carbonate, sodium hydrogen sulfate, and sodium sulfate.

4. A hydrophilic treatment method, comprising:

treating a surface layer that contains an inorganic compound with a silane coupling agent that contains at least one reactive functional group selected from an isocyanate group, an epoxy group, an amino group, and a mercapto group;

applying a hydrophilic treatment coating composition to the surface layer that is coupled with the silane coupling agent, the hydrophilic treatment coating composition containing a hydrophilic compound that contains a functional group that is at least one selected from an amino group, a hydroxyl group, and a mercapto group, and reacts with the reactive functional group of the silane coupling agent, and a sulfonic acid group, and which does not contain a hydrophilic portion at a site other than an end of a molecular chain, and a polar compatibilizer;

allowing the reactive functional group of the silane coupling agent and the functional group of the hydrophilic compound to react with each other with heat; and

allowing the sulfonic acid group of the hydrophilic compound to react with a hydroxide of an alkali metal to form sulphonate.